Liquid crystal display

ABSTRACT

The present invention relates to a liquid crystal display including a pixel electrode including a first subpixel electrode and a second subpixel electrode spaced apart with a gap therebetween, a common electrode facing the pixel electrode, and a liquid crystal layer formed between the pixel electrode and the common electrode and including a plurality of liquid crystal molecules. The first and second subpixel electrodes include a plurality of branches, and each of the first and second subpixel electrodes includes a plurality of subregions. The branches extend in different directions in different subregions.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/908,467, filed on Jun. 3, 2013, which is a continuation ofU.S. patent application Ser. No. 13/590,726, filed on Aug. 21, 2012, andissued as U.S. Pat. No. 8,462,305 on Jun. 11, 2013, which is acontinuation of U.S. patent application Ser. No. 13/230,329, filed onSep. 12, 2011, and issued as U.S. Pat. No. 8,253,908 on Aug. 28, 2012,which is a continuation of U.S. patent application Ser. No. 12/328,324,filed on Dec. 4, 2008, and issued as U.S. Pat. No. 8,035,787 on Oct. 11,2011, and claims priority from and the benefit of Korean PatentApplication No. 10-2008-0029090, filed on Mar. 28, 2008, which are allhereby incorporated by reference for all purposes as if fully set forthherein.

BACKGROUND OF THE INVENTION

1. Field Of the Invention

The present invention relates to a liquid crystal display.

2. Discussion of the Background

Liquid crystal displays (LCDs) are one of the most widely used flatpanel displays, and an LCD includes a pair of panels provided withfield-generating electrodes, such as pixel electrodes and a commonelectrode, and a liquid crystal (LC) layer disposed between the twopanels. The LCD displays images when voltages are applied to thefield-generating electrodes to generate an electric field in the LClayer, which determines the orientations of LC molecules therein,thereby adjusting the polarization of light incident thereto.

Among LCDs, a vertical alignment (VA) mode LCD, in which LC moleculesare aligned such that the long axes of the LC molecules areperpendicular to the panels in the absence of an electric field, hasbeen developed.

In a VA mode LCD, a wide viewing angle can be realized due to cutouts,such as slits in the field-generating electrodes and protrusions on thefield-generating electrodes. Since the cutouts and protrusions maydetermine the tilt directions of the LC molecules, the tilt directionsmay be distributed in several directions using the cutouts andprotrusions, thereby widening the reference viewing angle.

Also, a method for pretilting LC molecules in the absence of an electricfield has been developed to improve the response speed of the LCmolecules while realizing a wide viewing angle. For the LC molecules topretilt in various directions, alignment layers having various alignmentdirections may be used. Alternatively, the LC layer may be subjected toan electric field and a thermal or light-hardened material may be added.Then light may be irradiated onto the LC layer to harden the thermal orlight-hardening material, thereby pretilting the LC molecules.

However, the VA mode liquid crystal display may have lower sidevisibility compared with front visibility. To improve the sidevisibility, one pixel may be divided into two subpixels and differentvoltages may be applied to the subpixels.

SUMMARY OF THE INVENTION

The present invention provides a liquid crystal display that may have awide viewing angle and a fast response speed, as well as excellentvisibility and transmittance.

Additional features of the invention will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention.

The present invention discloses a liquid crystal display including apixel electrode including a first subpixel electrode and a secondsubpixel electrode spaced apart from each other with a gap therebetween,a common electrode facing the pixel electrode, and a liquid crystallayer disposed between the pixel electrode and the common electrode. Theliquid crystal layer includes a plurality of liquid crystal molecules,and the first and second subpixel electrodes include a plurality ofbranches. Each of the first and second subpixel electrodes includes aplurality of subregions, and the branches extend in different directionsin different subregions.

The present invention also discloses a liquid crystal display includinga pixel electrode including a first subpixel electrode and a secondsubpixel electrode spaced apart from each other with a gap therebetween,a common electrode facing the pixel electrode, and a liquid crystallayer disposed between the pixel electrode and the common electrode andincluding a plurality of liquid crystal molecules. The liquid crystallayer includes a first portion disposed between the first subpixelelectrode and the common electrode and a second portion disposed betweenthe second subpixel electrode and the common electrode. Each of thefirst and second portions includes a plurality of subregions, and theliquid crystal molecules are aligned in different directions indifferent subregions. Areas of the subregions are different from eachother in the first portion or in the second portion.

The present invention also discloses a liquid crystal display includinga first signal line and a second signal line, a third signal line and afourth signal line crossing the first and second signal lines, a pixelelectrode including a first subpixel electrode and a second subpixelelectrode spaced apart with a gap therebetween, a first switchingelement connected to the first signal line and the third signal line totransmit a data voltage from the third signal line to the first subpixelelectrode, a second switching element connected to the first signal lineand the fourth signal line to transmit a data voltage from the fourthsignal line to the second subpixel electrode, a common electrode facingthe pixel electrode, and a liquid crystal layer disposed between thepixel electrode and the common electrode and including a plurality ofliquid crystal molecules. One of the first subpixel electrode and thesecond subpixel electrode includes a plurality of branches, and the oneof the first subpixel electrode and the second subpixel electrodeincludes a plurality of subregions. The branches extend in differentdirections in different subregions.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention, andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is an equivalent circuit diagram of one pixel in a liquid crystaldisplay according to an exemplary embodiment of the present invention.

FIG. 2 is a layout view of a liquid crystal display according to anexemplary embodiment of the present invention.

FIG. 3 is a cross-sectional view of the liquid crystal display shown inFIG. 2 taken along line III-III.

FIG. 4 is a layout view of the liquid crystal display shown in FIG. 2without the pixel electrode.

FIG. 5 is a top plan view showing the pixel electrode of the liquidcrystal display show in FIG. 2.

FIG. 6 is a top plan view of a basic electrode of the pixel electrodeaccording to an exemplary embodiment of the present invention.

FIG. 7 is an enlarged view of the portion of the basic electrode shownin FIG. 6.

FIG. 8 is a view showing a process of pretilting liquid crystalmolecules using prepolymers polarized by light such as ultraviolet rays.

FIG. 9, FIG. 12, and FIG. 15 are layout views of a liquid crystaldisplay according to another exemplary embodiment of the presentinvention.

FIG. 10, FIG. 13, and FIG. 16 are layout views of the liquid crystaldisplays shown in FIG. 9, FIG. 12, and FIG. 15 without the pixelelectrodes.

FIG. 11, FIG. 14, and FIG. 17 are top plan views of the pixel electrodesin the liquid crystal displays shown in FIG. 9, FIG. 12, and FIG. 15.

FIG. 18 is a top plan view of a portion of a pixel electrode in a liquidcrystal display according to another exemplary embodiment of the presentinvention.

FIG. 19 is a top plan view of the portion of the pixel electrode shownin FIG. 18.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The invention is described more fully hereinafter with reference to theaccompanying drawings, in which embodiments of the invention are shown.This invention may, however, be embodied in many different forms andshould not be construed as limited to the embodiments set forth herein.Rather, these embodiments are provided so that this disclosure isthorough, and will fully convey the scope of the invention to thoseskilled in the art. In the drawings, the size and relative sizes oflayers and regions may be exaggerated for clarity. Like referencenumerals in the drawings denote like elements.

It will be understood that when an element or layer is referred to asbeing “on” or “connected to” another element or layer, it can bedirectly on or directly connected to the other element or layer, orintervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on” or “directly connected to”another element or layer, there are no intervening elements or layerspresent.

FIG. 1 is an equivalent circuit diagram of one pixel in a liquid crystaldisplay according to an exemplary embodiment of the present invention.

Referring to FIG. 1, a liquid crystal display according to an exemplaryembodiment of the present invention includes signal lines, which includea plurality of gate lines GL, a plurality of pairs of data lines DLa andDLb, and a plurality of storage electrode lines SL, and a plurality ofpixels PX connected to the signal lines. The liquid crystal displayincludes a lower panel 100 and an upper panel 200 facing each other, anda liquid crystal layer 3 disposed therebetween.

Each pixel PX includes a pair of subpixels PXa and PXb. Each subpixelPXa/PXb includes a switching element Qa/Qb, a liquid crystal capacitorClca/Clcb, and a storage capacitor Csta/Cstb.

Each switching element Qa/Qb is a three-terminal element, such as a thinfilm transistor, provided on a lower panel 100 and including a controlterminal connected to the gate line GL, an input terminal connected tothe data line DLa/DLb, and an output terminal connected to the liquidcrystal capacitor Clca/Clcb and the storage capacitor Csta/Cstb.

The liquid crystal capacitor Clca/Clcb uses a subpixel electrode and acommon electrode 270 as two terminals. The liquid crystal layer 3between the electrodes 191 a/191 b and 270 functions as a dielectricmaterial.

The storage capacitor Csta/Cstb serving as an assistant to the liquidcrystal capacitor Clca/Clcb includes a storage electrode line SL on thelower display panel 100, a subpixel electrode 191 a/191 b overlappingthe storage electrode line, and an insulator disposed therebetween. Avoltage, such as a common voltage Vcom, is applied to the storageelectrode line SL.

A difference is generated between the voltages charged to two liquidcrystal capacitors Clca and Clcb. For example, the data voltage appliedto the liquid crystal capacitor Clca may less than or greater than thedata voltage applied to the liquid crystal capacitor Clcb. Therefore,when the voltages of the first and second liquid crystal capacitors Clcaand Clcb are appropriately adjusted, it may be possible to make an imageviewed from the side as similar as possible to an image viewed from thefront, thereby improving the side visibility.

Next, a liquid crystal display according to an exemplary embodiment ofthe present invention will be described in detail with reference to FIG.2, FIG. 3, FIG. 4, FIG. 5, FIG. 6, and FIG. 7.

FIG. 2 is a layout view of a liquid crystal display according to anexemplary embodiment of the present invention, FIG. 3 is across-sectional view of the liquid crystal display shown in FIG. 2 takenalong line III-III, FIG. 4 is a layout view of the liquid crystaldisplay shown in FIG. 2 without the pixel electrode, FIG. 5 is a topplan view showing the pixel electrode of the liquid crystal display showin FIG. 2, FIG. 6 is a top plan view of a basic electrode of the pixelelectrode according to an exemplary embodiment of the present invention,and FIG. 7 is an enlarged view of a portion of the basic electrode shownin FIG. 6.

Referring to FIG. 2 and FIG. 3, a liquid crystal display according to anexemplary embodiment of the present invention includes a lower panel 100and an upper panel 200 facing each other, and a liquid crystal layer 3disposed between the two panels 100 and 200.

First, the lower panel 100 will be described.

A plurality of gate lines 121 and a plurality of storage electrode lines131 are formed on an insulating substrate 110.

The gate lines 121 transmit gate signals and extend in a transversedirection. Each gate line 121 includes a plurality of first and secondgate electrodes 124 a and 124 b protruding upward.

The storage electrode lines 131 include a stem extending substantiallyparallel to the gate lines 121, and a plurality of branches extendingfrom the stem. Each branch includes a longitudinal portion 137, a loop135, a first storage electrode 133 a, and a second storage electrode 133b.

The longitudinal portion 137 extends upward and downward from the stem(hereinafter, an imaginary straight line in the direction in which thelongitudinal portion 137 extends is referred to as a “longitudinalcenter line”).

The loop 135 may be substantially rectangular, and the upper edgethereof vertically may meet the longitudinal portion 137.

The first storage electrode 133 a extends in a transverse direction fromthe center of the left edge of the loop 135 to the center of the rightedge, and may have a wider width than the longitudinal portion 137 orthe loop 135. The first storage electrode 133 a and the longitudinalportion 137 vertically meet each other.

The left edge of the loop 135 extends downward and curves to the rightto form the second storage electrode 133 b. The width of the secondstorage electrode 133 b is expanded and extends substantially parallelto the first storage electrode 133 a in the transverse direction.

However, the shapes and arrangement of the storage electrode lines 131may be modified in various forms.

A gate insulating layer 140 is formed on the gate lines 121 and thestorage electrode lines 131 and a plurality of semiconductors 154 a and154 b, which may be made of amorphous or crystallized silicon, areformed on the gate insulating layer 140.

A pair of ohmic contacts 163 b and 165 b are formed on the firstsemiconductor 154 b, and the ohmic contacts 163 b and 165 b may beformed of a material such as n+ hydrogenated amorphous silicon in whichan n-type impurity is doped with a high concentration or silicide.

A pair of data lines 171 a and 171 b and a plurality of first and seconddrain electrodes 175 a and 175 b are formed on the ohmic contacts 163 band 165 b, and on the gate insulating layer 140.

The data lines 171 a and 171 b transmit data signals, extendsubstantially in the longitudinal direction, and cross the gate lines121 and the storage electrode lines 131. Each data line 171 a/171 bincludes a plurality of first/second source electrode 173 a/173 bextending toward the first/second gate electrode 124 a/124 b and curvingwith a “U” shape, and the first/second source electrode 173 a/173 b isopposite the first/second drain electrode 175 a/175 b with respect tothe first/second gate electrode 124 a/124 b.

Each first drain electrode 175 a has one end enclosed by the firstsource electrode 173 a from which it extends upward, curves to the leftfollowing the upper edge of the second storage electrode 133 b, andagain extends upward near the longitudinal center line to form the otherend. The other end of the first drain electrode 175 a extends to wherethe second storage electrode 133 b is disposed, and has a wide area forconnection with another layer.

Each second drain electrode 175 b has one end enclosed by the secondsource electrode 173 b from which it extends upward to the secondstorage electrode 133 b, curves to the right, extends following thelower edge of the second storage electrode 133 b, expands with a widearea near the longitudinal center line, and again extends downward toform a longitudinal portion 176.

However, the shapes and arrangement of the first and second drainelectrodes 175 a and 175 b and the data lines 171 a and 171 b may bemodified in various ways.

A first/second gate electrode 124 a/124 b, a first/second sourceelectrode 173 a/173 b, and a first/second drain electrode 175 a/175 brespectively form a first/second thin film transistor (TFT) Qa/Qb alongwith a first/second semiconductor 154 a/154 b, and a channel of thefirst/second thin film transistor Qa/Qb is formed on the first/secondsemiconductor 154 a/154 b between the first/second source electrode 173a/173 b and the first/second drain electrode 175 a/175 b.

The ohmic contacts 163 b and 165 b are disposed only between theunderlying semiconductor islands 154 a and 154 b and the overlying datalines 171 a and 171 b and drain electrodes 175 a and 175 b, and mayreduce contact resistance between them. The semiconductors 154 a and 154b each have a portion that is exposed without being covered by the datalines 171 a and 171 b and the drain electrodes 175 a and 175 b, and aportion between the source electrodes 173 a and 173 b and the drainelectrodes 175 a and 175 b.

A lower passivation layer 180 p, which may be made of silicon nitride orsilicon oxide, is formed on the data lines 171 a and 171 b, the drainelectrodes 175 a and 175 b, and the exposed portions of thesemiconductors 154 a and 154 b.

A black matrix including a plurality of light blocking members 220spaced at intervals from each other is formed on the lower passivationlayer 180 p. Each light blocking member 220 may include a stripe portionextending upward and downward, and a quadrangle portion corresponding tothe thin film transistor to prevent light leakage.

A plurality of color filters 230 are formed on the lower passivationlayer 180 p and the light blocking members 220. The color filters 230are mostly formed in a region surrounded by light blocking members 220.The color filters 230 have a plurality of holes 235 a and 235 b disposedon the first and second drain electrodes 175 a and 175 b, and aplurality of openings 233 a and 233 b disposed on the first and secondstorage electrodes 133 a and 133 b, respectively. The opening 233 a and233 b reduce the thickness of the dielectric material forming thestorage capacitors Csta and Cstb such that the storage capacitance maybe increased.

Here, the lower passivation layer 180 p may prevent pigments of thecolor filter 230 from flowing into the exposed semiconductors 154 a and154 b.

An upper passivation layer 180 q is formed on the light blocking members220 and the color filters 230. The upper passivation layer 180 q may bemade of an inorganic insulating material, such as silicon nitride orsilicon oxide, and may prevent the color filters 230 from lifting andsuppress the contamination of the liquid crystal layer 3 by the organicmaterial, such as a solvent flowing from the color filters 230, sodefects generated during driving, such as an afterimage, may beprevented.

However, at least one of the light blocking members 220 and the colorfilters 230 may be disposed on the upper panel 200, and one of the lowerpassivation layer 180 p and the upper passivation layer 180 q of thelower panel 100 may be omitted in this case.

The upper passivation layer 180 q and the lower passivation layer 180 phave a plurality of contact holes 185 a and 185 b respectively exposingthe first and second drain electrodes 175 a and 175 b.

A plurality of pixel electrodes 191 is formed on the upper passivationlayer 180 q, and the above-described color filters 230 may extendaccording to a column of the pixel electrodes 191.

Referring to FIG. 5, each pixel electrode 191 includes the first andsecond subpixel electrodes 191 a and 191 b that are spaced apart fromeach other with a gap 91 having a quadrangular belt shape therebetween,and the first and second subpixel electrodes 191 a and 191 brespectively include a basic electrode 199 shown in FIG. 6, or at leastone modification thereof.

Next, the basic electrode 199 will be described in detail with referenceto FIG. 6.

As shown in FIG. 6, the basic electrode 199 may be a quadrangle and mayinclude a cross-shaped stem having a transverse stem 193 that crosses alongitudinal stem 192. Also, the basic electrode 199 is divided into afirst subregion Da, a second subregion Db, a third subregion Dc, and afourth subregion Dd by the transverse stem 193 and the longitudinal stem192, and each subregion Da-Dd includes a plurality of first, second,third, and fourth branches 194 a, 194 b, 194 c, and 194 d.

The first branch 194 a extends obliquely from the transverse stem 193 orthe longitudinal stem 192 in the upper-left direction, as shown in FIG.7, and the second branch 194 b extends obliquely from the transversestem 193 or the longitudinal stem 192 in the upper-right direction.Also, the third branch 194 c extends obliquely from the transverse stem193 or the longitudinal stem 192 in the lower-left direction, and thefourth branch 194 d extends obliquely from the transverse stem 193 orthe longitudinal stem 192 in the lower-right direction.

The first, second, third, and fourth branches 194 a, 194 b, 194 c, and194 d form an angle of about 45 degrees or 135 degrees with the gatelines 121 or the transverse stem 193. Also, the branches 194 a, 194 b,194 c, and 194 d of two neighboring subregions Da, Db, Dc, and Dd may becrossed.

The width of the branches 194 a, 194 b, 194 c, and 194 d may be in therange of 2.5 μm to 5.0 μm, and the interval between the neighboringbranches 194 a, 194 b, 194 c, and 194 d in one subregion Da, Db, Dc, andDd may be in the range of 2.5 μm to 5.0 μm.

Also, referring to FIG. 7, the width of the branches 194 a, 194 b, 194c, and 194 d may become wider approaching the transverse stem 193 or thelongitudinal stem 192, and the difference between the widest width andthe narrowest width in one of the branches 194 a, 194 b, 194 c, and 194d may be in the range of 0.2 μm to 1.5 μm.

Again, referring to FIG. 2, FIG. 3, FIG. 4, and FIG. 5, the firstsubpixel electrode 191 a includes one basic electrode 199 as shown inFIG. 6. The transverse stem 193 of the basic electrode 199 forming thefirst subpixel electrode 191 a expands downward and upward to form afirst expansion 193 a, and the first expansion 193 a overlaps the firststorage electrode 133 a. Also, the protrusion that protrudes downward tocontact the first drain electrode 175 a is formed in the center of thedownward edge of the first expansion 193 a.

The second subpixel electrode 191 b includes an upper electrode 191 buand a lower electrode 191 bb, and each of the upper electrode 191 bu andthe lower electrode 191 bb includes one basic electrode 199. The upperelectrode 191 bu and the lower electrode 191 bb are connected to eachother through left and right connections 195 b.

The second subpixel electrode 191 b encloses the first subpixelelectrode 191 a with the gap 91 therebetween. A portion of the center ofthe transverse stem of the lower electrode 191 bb extends upward anddownward to form a second expansion 193 bb overlapping the secondstorage electrode 133 b. Also, the protrusion that protrudes downward tocontact the second drain electrode 175 b is formed in the center of thedownward edge of the second expansion 193 bb.

The area of the second subpixel electrode 191 b may be about 1.0 to 2.2times the area of the first subpixel electrode 191 a.

Each first/second subpixel electrode 191 a/191 b is connected to thefirst/second drain electrode 175 a/175 b through the contact hole 185a/185 b, and receives data voltages from the first/second drainelectrode 175 a/175 b.

On the other hand, the upper electrode 191 bu may receive the datavoltages directly from the second drain electrode 175 b. In this case,the second drain electrode 175 b extends to the upper electrode 191 bu,and a contact hole (not shown) through which the upper electrode 191 bucontacts the second drain electrode 175 b is required. In this case, theleft and right connections 195 b are not necessary.

An alignment layer 11 is formed on the pixel electrodes 191.

Next, the upper panel 200 will be described.

A common electrode 270 is formed on an insulating substrate 210, and analignment layer 21 is formed thereon.

Each alignment layer 11 and 21 may be a vertical alignment layer.

Finally, polarizers (not shown) may be provided on the outer surface ofthe display panels 100 and 200.

The liquid crystal layer 3 disposed between the lower panel 100 and theupper panel 200 includes liquid crystal molecules 310 and polymers 350and 370 having negative dielectric anisotropy.

The liquid crystal molecules 310 are pretilted by the polymers 350 and370 for the long axis thereof to be parallel to the directions in whichthe first, second, third, and fourth branches 194 a, 194 b, 194 c, and194 d of the first and second subpixel electrode 191 a and 191 b extend,and are aligned vertically with respect to the surface of the two panels100 and 200. Accordingly, the first and second subpixels PXa and PXbeach include four subregions Da, Db, Dc, and Dd in which the liquidcrystal molecules 310 are pretilted in different directions.

If the gate lines 121 are applied with the gate signals, the datavoltage is applied to the first and second subpixel electrodes 191 a and191 b through the data lines 171 a and 171 b. Then, the first and secondsubpixel electrodes 191 a and 191 b receive the data voltage and thecommon electrode 270 receives the common voltage, thereby generating anelectric field in the liquid crystal layer 3. Accordingly, the liquidcrystal molecules 310 of the liquid crystal layer 3 are arranged inresponse to the electric field such that the major axes of the liquidcrystal molecules 310 change direction to be perpendicular to thedirection of the electric field. The degree to which the polarization oflight incident to the liquid crystal layer 3 changes depends on theinclination degree of the liquid crystal molecules 310, and the changein the polarization is represented by a change in the transmittance by apolarizer, thereby causing the liquid crystal display to display animage.

On the other hand, the edges of the branches 194 a, 194 b, 194 c, and194 d distort the electric field to make the horizontal componentsperpendicular to the edges of the branches 194 a, 194 b, 194 c, and 194d, and the alignment of the liquid crystal molecules 310 is determinedby the horizontal components. Accordingly, the liquid crystal molecules310 first tend to tilt in a direction perpendicular to the edges of thebranches 194 a, 194 b, 194 c, and 194 d. However, the directions of thehorizontal components of the electric field by the neighboring branches194 a, 194 b, 194 c, and 194 d are opposite to each other and theintervals between the branches 194 a, 194 b, 194 c, and 194 d are narrowsuch that the liquid crystal molecules 310, which tend to arrange inopposite directions, are tilted in the direction parallel to thedirections in which the branches 194 a, 194 b, 194 c, and 194 d extend.Accordingly, if the liquid crystal molecules 310 are not initiallypretilted in the direction in which the branches 194 a, 194 b, 194 c,and 194 d extend, the liquid crystal molecules 310 may be tilted in thedirections in which the branches 194 a, 194 b, 194 c, and 194 d extendthrough two steps. However, in the present exemplary embodiment, theliquid crystal molecules 310 are already pretilted in a directionparallel to the directions of in which branches 194 a, 194 b, 194 c, and194 d extend so the liquid crystal molecules 310 are pretilted in onestep. Therefore, if the liquid crystal molecules 310 are pretilted, theymay be tilted in the required direction in one step such that theresponse speed of the liquid crystal display may be improved.

Also, in an exemplary embodiment of the present invention, the branches194 a, 194 b, 194 c, and 194 d extend in different directions in onepixel PX such that the liquid crystal molecules 310 are inclined in fourdirections. Therefore, the viewing angle of the liquid crystal displaymay be widened by varying the inclined directions of the liquid crystalmolecules.

The first/second sub-pixel electrode 191 a/191 b and the commonelectrode 270 form the liquid crystal capacitor Clca/Clcb to maintain anapplied voltage even after the TFT is turned off. Also, the first andsecond storage electrodes 133 a and 133 b of the storage electrode line131 respectively overlap the first and second subpixel electrodes 191 aand 191 b in the openings 188 a and 188 b to form the storage capacitorsCsta and Cstb.

The loop 135 of the storage electrode line 131 overlaps the gap 91 ofthe pixel electrode 191 such that it functions as a shielding member toblock light leakage between the first subpixel electrode 191 a and thesecond subpixel electrode 191 b. The loop 135 disposed between the datalines 171 a and 171 b, and the first subpixel electrode 191 a, mayprevent crosstalk, which may reduce degradation of the display quality.

Also, in the structure of pixel electrode 191 in an exemplary embodimentof the present invention, the alignment of the liquid crystal molecules310 may not be controlled near the longitudinal and the transverse stemsof the first and second subpixel electrodes 191 a and 191 b so texturemay be generated. Accordingly, the storage electrode line 131, thelongitudinal portion 137 of the storage electrode line 131, and thefirst and second storage electrodes 133 a and 133 b overlap thetransverse stem or the longitudinal stem of the first and secondsubpixel electrodes 191 a and 191 b such that the texture may becovered, so the aperture ratio may be increased.

On the other hand, the first subpixel electrode 191 a and the secondsubpixel electrode 191 b are applied with different data voltagesthrough the different data lines 171 a and 171 b, and the voltage of thefirst subpixel electrode 191 a having a relatively small area is higherthan the voltage of the second subpixel electrode 191 b having arelatively large area.

In this way, if the voltages of the first sub-pixel electrode 191 a andthe second sub-pixel electrode 191 b are different from each other, thevoltage applied to the first liquid crystal capacitor Clca formedbetween the first sub-pixel electrode 191 a and the common electrode 270and the voltage applied to the second liquid crystal capacitor Clcbformed between the second sub-pixel electrode 191 b and the commonelectrode 270 are different from each other such that the declinationangle of the liquid crystal molecules of the subpixels PXa and PXb aredifferent from each other, and as a result the luminance of the twosubpixels become different. Accordingly, if the voltages of the firstand second liquid crystal capacitors Clca and Clcb are appropriatelycontrolled, the images shown at the side may be approximate to the imageshown at the front, that is to say, the gamma curve of the side may beapproximately close to the gamma curve of the front, which may improvethe side visibility.

Also, in an exemplary embodiment of the present invention, if the firstsubpixel electrode 191 a applied with the higher voltage is disposed inthe center of the pixel PX, the first subpixel electrode 191 a is fatherapart from the gate line 121 such that an overlapping portiontherebetween is not generated, which may reduce a kick-back voltage andremove flicker.

Next, the alignment method for initially pretilting liquid crystalmolecules 310 will be described with reference to FIG. 8.

FIG. 8 is a view showing a process for pretilting liquid crystalmolecules using prepolymers, which are polymerized by light such asultraviolet rays.

First, prepolymers 330, such monomers, which are hardened throughpolymerization by light such as ultraviolet rays, are inserted betweenthe two display panels 100 and 200 along with the liquid crystalmaterial. The prepolymers 330 may include reactive mesogen that ispolymerized by light, such as ultraviolet rays.

Next, the first and second subpixel electrodes 191 a and 191 b receivethe data voltages and the common electrode 270 of the upper panel 200receives the common voltage to generate an electric field to the liquidcrystal layer 3 between two display panels 100 and 200. Thus, the liquidcrystal molecules 310 of the liquid crystal layer 3 are inclined in adirection parallel to the length direction of the branches 194 a, 194 b,194 c, and 194 d through two steps, as above-described, in response tothe electric field, and the liquid crystal molecules 310 in one pixel PXare inclined in a total of four directions.

If the liquid crystal layer 3 is irradiated, for example, withultraviolet rays, after the application of the electric field to theliquid crystal layer 3, the prepolymers 330 are polymerized such thatthe first polymer 350 and the second polymer 370 are formed as shown inFIG. 8.

The first polymer 350 is formed in the liquid crystal layer 3, and thesecond polymer 370 is formed close to the display panels 100 and 200.The liquid crystal molecules 310 are pretilted in the directions inwhich the branches 194 a, 194 b, 194 c, and 194 d extend by the firstand second polymers 350 and 370.

Accordingly, the liquid crystal molecules 310 are arranged to pretilt infour different directions when no voltage is applied to the electrodes191 and 270.

Next, another exemplary embodiment of the present invention will bedescribed with the reference to FIG. 9, FIG. 10, and FIG. 11.

FIG. 9 is a layout view of a liquid crystal display according to anotherexemplary embodiment of the present invention, FIG. 10 is a layout viewof the liquid crystal display shown in FIG. 9 without the pixelelectrode, and FIG. 11 is a top plan view showing the pixel electrode ofthe liquid crystal display shown in FIG. 9.

The layered structure of the liquid crystal display according to thepresent exemplary embodiment is almost the same as the layered structureof the liquid crystal display shown in FIG. 2, FIG. 3, FIG. 4, and FIG.5.

Referring to FIG. 9, FIG. 10, and FIG. 11, the storage electrode line131 includes left and right longitudinal portions 138 extending downwardfrom the storage electrode line 131, and a storage electrode 133protruding in the right direction from the left longitudinal portion138. The storage electrode 133 has the wider width than that of theother portion for overlapping with a pixel electrode 191 to be describedbelow.

The first drain electrode 175 a includes one end having a wide areaextending a long distance upward, and the second drain electrode 175 bincludes one end having a wide area extending a short distance upward.

The color filters (not shown) have through holes 235 a and 235 b wherecontact holes 185 a and 185 b pass through and an opening 233 disposedon the storage electrode 133, and an upper passivation layer (not shown)and a lower passivation layer (not shown) have a plurality of contactholes 185 a and 185 b to expose the first and second drain electrodes175 a and 175 b.

The pixel electrode 191 according to the present exemplary embodimentalso includes first and second subpixel electrodes 191 a and 191 b thatare spaced apart from each other with a gap 91 having a quadrangularbelt shape, like the exemplary embodiment shown in FIG. 2, FIG. 3, FIG.4, and FIG. 5.

The first subpixel electrode 191 a is made of one basic electrode 199,as shown in FIG. 6. A transverse stem of the first subpixel electrode191 a expands upward and downward to form an expansion 193 c, and theexpansion 193 c overlaps the storage electrode 133 in an opening 233 toform a storage capacitor Csta.

The second subpixel electrode 191 b includes one basic electrode 199,and a connection bridge 196 b enclosing the first subpixel electrode 191a, which is disposed below the second subpixel electrode 191 b with agap 91 therebetween.

The left lower portion of the connection bridge 196 b protrudes to theright with a wide area to contact the second drain electrode 175 b. Asshown in FIG. 9, the second subpixel electrode 191 b receives datavoltages from the second drain electrode 175 b through the connectionbridge 196 b.

The lower transverse edge of the connection bridge 196 b overlaps aportion of the gate line 121 to prevent the first subpixel electrode 191a from being influenced by the gate signals of the gate lines 121.

Both longitudinal edges of the connection bridge 196 b cover the datalines 171 a and 171 b to prevent cross talk between the data signal andthe first subpixel electrode 191 a.

The width of the connection bridge 196 b may be in the range of 5.0 μmto 15 μm.

The storage electrode line 131 overlaps the gap 91 of the pixelelectrode 191 to block light leakage between the first subpixelelectrode 191 a and the second subpixel electrode 191 b. Also, the rightand left longitudinal portions 138 of the storage electrode line 131 aredisposed between the first subpixel electrode 191 a and the data lines171 a and 171 b, to prevent cross talk between the data lines 171 a and171 b and the first subpixel electrode 191 a.

The area of the second subpixel electrode 191 b may be about 1.25 to2.75 times the area of the first subpixel electrode 191 a.

Unlike the above-described exemplary embodiment, according to thepresent exemplary embodiment, the first/second drain electrode 175 a/175b do not overlap the second/first subpixel electrode 191 b/191 a thatreceive data voltages having different polarities from each other, butinstead overlap only the first/second subpixel electrode 191 a/191 bthat receive data voltages having the same polarity such that a texturedue to distortion of the electric field is not generated near the firstand second drain electrodes 175 a and 175 b even though the first andsecond data lines 171 a and 171 b receive data voltages of oppositepolarities. Accordingly, texture may be prevented, which may increasetransmittance.

Also, according to the present exemplary embodiment, the contact holes185 a and 185 b are disposed at edges or corners of the first and secondsubpixel electrodes 191 a and 191 b so that it may be easy to form colorfilters (not shown) by an inkjet printing process.

Like the above described exemplary embodiment, the liquid crystalmolecules are inclined in four directions such that the viewing angle ofthe liquid crystal display may be increased, and the liquid crystalmolecules are pretilted through the polymerization of the prepolymersuch that the response speed may be improved. Also, the first and secondsubpixel electrodes 191 a and 191 b receive different data voltages,which may improve side visibility.

Next, another exemplary embodiment of the present invention will bedescribed with reference to FIG. 12, FIG. 13, and FIG. 14.

FIG. 12 is a layout view of a liquid crystal display according toanother exemplary embodiment of the present invention, FIG. 13 is alayout view of the liquid crystal display shown in FIG. 12 without thepixel electrode, and FIG. 14 is a top plan view showing the pixelelectrode of the liquid crystal display shown in FIG. 12.

A liquid crystal display according to the present exemplary embodimentis almost the same as the liquid crystal display shown in FIG. 9, FIG.10, and FIG. 11.

Referring to FIG. 12, FIG. 13, and FIG. 14, the wide end portion of thefirst drain electrode 175 a to apply the data voltage to the firstsubpixel electrode 191 a is disposed at the right lower corner of thefirst subpixel PXa, and is connected to the first subpixel electrode 191a through the contact hole 185 a. Accordingly, when forming the colorfilter (not shown) through an inkjet printing process, the process maybe easily executed and the transmittance may be improved.

Also, the storage electrodes and the openings having a wide area to formthe storage capacitors Csta and Cstb do not exist in the presentexemplary embodiment, which may increase the aperture ratio.

Next, another exemplary embodiment of the present invention will bedescribed with reference to FIG. 15, FIG. 16, and FIG. 17.

FIG. 15 is a layout view of a liquid crystal display according toanother exemplary embodiment of the present invention, FIG. 16 is alayout view of the liquid crystal display shown in FIG. 15 except forthe pixel electrode, and FIG. 17 is a top plan view showing the pixelelectrode of the liquid crystal display shown in FIG. 15.

The layered structure of the liquid crystal display according to thepresent exemplary embodiment is almost the same as the layered structureof the liquid crystal display shown in FIG. 2, FIG. 3, FIG. 4, and FIG.5.

Referring to FIG. 15, FIG. 16, and FIG. 17, the storage electrode line131 includes left and right longitudinal portions 139 that extend upwardand downward from the storage electrode line 131, a transverseconnection 132 connected between two longitudinal portions 139, and astorage electrode 133 c protruding from the center of the transverseconnection 132 to the lower direction and having a wide area.

The color filters (not shown) have through holes 235 a and 235 b wherecontact holes 185 a and 185 b pass through, and an opening 233 disposedon the storage electrode 133 c, and an upper passivation layer (notshown) and a lower passivation layer (not shown) have a plurality ofcontact holes 185 a and 185 b exposing the first and second drainelectrodes 175 a and 175 b.

The pixel electrode 191 also includes the first and second subpixelelectrodes 191 a and 191 b that are spaced apart from each other with agap 91 having a quadrangular belt shape.

The second subpixel electrode 191 b includes an upper electrode 191 buand a lower electrode 191 bb, and the upper electrode 191 bu and thelower electrode 191 bb are connected through left and right connections195 b.

Two longitudinal portions 139 of the storage electrode line 131 overlapthe gap 91 to block light leakage between the first subpixel electrode191 a and the second subpixel electrode 191 b and prevent cross talkbetween the first subpixel electrode 191 a and the data lines 171 a and171 b. Also, the transverse connection 132 of the storage electrode line131 covers the texture near the transverse stem 193 d of the firstsubpixel electrode 191 a, which may improve the aperture ratio.

In the present exemplary embodiment, different from the exemplaryembodiment shown in FIG. 2, FIG. 3, FIG. 4, and FIG. 5, a transversestem 193 du of the upper electrode 191 bu is not disposed on the centerof the upper electrode 191 bu, but is near the upper edge, and thetransverse stem 193 db of the lower electrode 191 bb is disposed nearthe lower edge of the lower electrode 191 bb. Accordingly, as for eachof the upper and lower electrodes 191 bu and 191 bb, two subregionsamong four subregions Da, Db, Dc, and Dd of the basic electrode 199 ofFIG. 6 as above-described almost disappear and remain as dummies.However, all of the subregions Da, Db, Dc, and Dd still exist in thesecond subpixel electrode 191 b such that the liquid crystal molecules310 may be inclined in four directions.

In this case, the area of the two remaining subregions Dc and Dd of theupper electrode 191 bu may be more than 1.5 times the area of the twosubregions Da and Db, which become small. The area of the two remainingsubregions Da and Db of the lower electrode 191 bb may be more than 1.5times the area of the two subregions Dc and Dd, which may become small.

Also, the length between the upper edge and the lower edge of the twosubregions Da and Db of the upper electrode 191 bu or two subregions Dcand Dd of the lower electrode 191 bb, which may become small, may beabout 5 μm.

Like the present exemplary embodiment, two subregions Da and Db of theupper electrode 191 bu or two subregions Dc and Dd of the lowerelectrode 191 bb overlap the gate line 121 as dummies such that theaperture ratio and the transmittance may be increased and texture may becovered near the transverse stems 193 du and 193 db.

The reason why the two subregions Da and Dd, which are almost eliminatedbut remain as dummies, will be described with reference to FIG. 18 andFIG. 19.

FIG. 18 is a top plan view of a portion of a pixel electrode in a liquidcrystal display according to another exemplary embodiment of the presentinvention, and FIG. 19 is a top plan view of the portion of the pixelelectrode shown in FIG. 17.

As shown in FIG. 18, if two subregions Da and Db of the upper electrode191 bu are altogether removed, a fringe field is generated in thedirection D1 vertical to the upper edge of the upper electrode 191 bu.Thus, disclination DL of the liquid crystal molecules 310 may generated,which may generate a texture because the inclined direction D2 of theliquid crystal molecules 310 in the two subregions Dc and Dd discordwith the direction D1 of the fringe field.

However, as shown in FIG. 19, if the two subregions Da and Db are leftas dummies at the top of the upper electrode 191 bu, the liquid crystalmolecules 310 are inclined in the direction D1 such that the horizontalinclination direction of the liquid crystal molecules 310 of thesubregions Da and Db is the same as that of the liquid crystal molecules310 of the subregions Dc and Dd, and thereby the texture may beweakened.

The longitudinal stems 192 du and 192 db of the upper and the lowerelectrodes 191 bu and 191 bb of the second subpixel electrode 191 b maybe positioned near the left edge or the right edge of the pixel PX,instead of locating the transverse stems 193 du and 193 db of the upperor lower electrodes 191 bu or 191 bb of the second subpixel electrode191 b near the upper and lower edges of the pixel PX like the presentexemplary embodiment, such that a difference between the areas of theleft subregions Da and Dc and the right subregions Db and Dd may begenerated. In this case, the area of the subregions which become wide,may be more than 1.5 times the area of the subregions which becomesmall.

Also, according to the present exemplary embodiment, differently fromthe exemplary embodiment shown in FIG. 2, FIG. 3, FIG. 4, and FIG. 5,the transverse stem 193 of the first subpixel electrode 191 a does notinclude the expanded portion, and the portion disposed under thelongitudinal stem 192 expands at both sides to form a third expansion192 a. Also, the a portion to contact with the first drain electrode 175a is formed under the third expansion 192 a, and another wide portionfor the contact with the second drain electrode 175 b is formed at thebottom of the longitudinal stem 192 db of the lower electrode 191 bb ofthe second subpixel electrode 191 b.

In the present exemplary embodiment, as in the previously describedexemplary embodiment, the liquid crystal molecules are inclined in fourdirections so that the viewing angle of the liquid crystal display maybe increased, and the liquid crystal molecules are pretilted by thepolymerization of the prepolymer, which may improve the response speed.Also, the first and second subpixel electrodes 191 a and 191 b receivedifferent data voltages, which may improve side visibility.

Different from an exemplary embodiment of the present invention, a lightalignment method in which light such as ultraviolet rays is obliquelyirradiated to the alignment layers 11 and 21 may be used to control thealignment direction and the alignment angle of the liquid crystalmolecules 310 to form a plurality of subregions Da, Db, Dc, and Dd wherethe liquid crystal molecules 310 are inclined in different directions.In this case, the branches 194 a, 194 b, 194 c, and 194 d of the pixelelectrodes 191 are not necessary to increase the aperture ratio andimprove the response time due to the pretilt of the liquid crystalmolecules 310, which is generated by light alignment.

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A liquid crystal display, comprising: a pluralityof pixels, each of the plurality of pixels comprising a pixel electrodecomprising a first pixel electrode electrically connected to one of afirst transistor and a second transistor and a second pixel electrodeelectrically connected to the other one of the first transistor and thesecond transistor, the first pixel electrode and the second pixelelectrode being separated from each other; a common electrode facing thepixel electrode; a liquid crystal layer disposed between the pixelelectrode and the common electrode, the liquid crystal layer comprisinga plurality of liquid crystal molecules, the liquid crystal moleculesbeing substantially vertically aligned with respect to a plane of thepixel electrode or the common electrode in the absence of an electricfield in the liquid crystal layer; and an alignment layer disposed onthe pixel electrode, wherein the alignment layer is irradiated by lightto generate pretilt of the liquid crystal molecules, wherein the liquidcrystal layer on at least one of the first pixel electrode and thesecond pixel electrode is divided into first, second, third, and fourthdomains, and wherein each of the first, second, third, and fourthdomains is defined by an orientation direction of the liquid crystalmolecules when a voltage is applied to at least one of the first pixelelectrode and the second pixel electrode.
 2. The liquid crystal displayof claim 1, further comprising: a passivation layer disposed under thepixel electrode; and a storage electrode line extending across the pixelelectrode, wherein the passivation layer comprises a contact holeoverlapping a portion of the storage electrode line.
 3. The liquidcrystal display of claim 2, further comprising: a drain electrodedisposed under the passivation layer, wherein the contact hole exposesthe drain electrode, and wherein the drain electrode is electricallyconnected to the pixel electrode through the contact hole.
 4. The liquidcrystal display of claim 3, wherein: the drain electrode comprises afirst portion and a second portion, the first portion is substantiallyparallel to a gate line extending in a first direction; and the secondportion is substantially parallel to a data line extending in a seconddirection.
 5. The liquid crystal display of claim 3, wherein the contacthole is disposed at a central portion of the pixel electrode.
 6. Theliquid crystal display of claim 5, wherein a portion of the storageelectrode line overlaps a portion of the drain electrode.
 7. The liquidcrystal display of claim 5, wherein a portion of the storage electrodeline is disposed between the first domain and the second domain.
 8. Theliquid crystal display of claim 7, wherein a portion of the drainelectrode is disposed between the first domain and the third domain. 9.The liquid crystal display of claim 5, wherein a portion of the drainelectrode is disposed between the first domain and the third domain. 10.The liquid crystal display of claim 1, further comprising: a drainelectrode comprising a first portion and a second portion, wherein thefirst portion is substantially parallel to a gate line extending in afirst direction, and wherein the second portion is substantiallyparallel to a data line extending in a second direction.
 11. The liquidcrystal display of claim 1, further comprising: a storage electrode lineextending across the pixel electrode; and a drain electrode electricallyconnected to the pixel electrode through a contact hole, wherein aportion of the storage electrode line overlaps a portion of the drainelectrode.
 12. The liquid crystal display of claim 1, furthercomprising: a storage electrode line extending across the pixelelectrode, wherein a portion of the storage electrode line is disposedbetween the first domain and the second domain.
 13. The liquid crystaldisplay of claim 12, further comprising: a drain electrode electricallyconnected to the pixel electrode, wherein a portion of the drainelectrode is disposed between the first domain and the third domain. 14.The liquid crystal display of claim 1, further comprising: a drainelectrode electrically connected to the pixel electrode, wherein aportion of the drain electrode is disposed between the first domain andthe third domain.